World War I

Question:

Answer:

The Russian revolution, with the overthrow of the Czar and subsequent
civil war, led to Russia signing a separate peace treaty and withdrawing
from the fighting. This allowed Germany to send troops from the Eastern
Front along the Russian border to the Western Front to swell the number of
troops already fighting in France. This might have tilted the war in
Germany's favor except for the entry of the USA into the war on the side of
the Allies (France, Britain, and others.)
The war in Europe